I say "Give me 5." I have a poster that asks for 1) Mouths closed. 2) Eyes on me. 3) Hands folded. 4) Ears listening to me. 5) Bottom in chair. Some times I don't even say it, I will just stand in front of the room and hold up 5 fingers. Once one student sees me they all start telling each other to stop and give me 5.

I also do a verbal call I got off of here:
Me: "Ba da ba ba ba."
Them: "I'm lovin' it!"

I've done different ones over the years. This year I do a sing song one Hey (me) Ho (them). My teacher friend does the shave and a haircut song without the words: Bum budda bum bum (her) Bum bum (kids). At a conference I heard a spelling one that goes like this: L - I - S (teacher) T - E - N (kids).

All I do is say in a normal (sometimes very quiet) voice "If you can hear me, please be quiet." I usually say it about 3 times and the whole room will be silent, even if they had been very noisy! I'm always amazed at how well it works!